The invention pertains to digital data processing and, more particularly, to high-speed access to and sharing of disk drives and other storage devices on a networked digital data processing system. The invention has application, for example, in accessing and sharing video, graphics and other large data files on a networked computer system.
In early computer systems, long-term data storage was typically accomplished via dedicated storage devices, such as tape and disk drives, connected to a data central computer. Requests to read and write data generated by applications programs were processed by special-purpose input/output routines resident in the computer operating system. With the advent of "time sharing" and other early multiprocessing techniques, multiple users could simultaneously store and access data--albeit only through the central storage devices.
With the rise of the personal computer (and workstation) in the 1980's, demand by business users led to development of interconnection mechanisms that permitted otherwise independent computers to access on one another's storage devices. Though computer "networks" had been known prior to this, they typically permitted only communications, not storage sharing.
Increases in the power of the personal computer is opening ever more avenues for their use. Video editing applications, for example, have until recently demanded specialized video production systems. Now, however, such applications can be run on high-end personal computers. By coupling these into a network, multiple users can share and edit a single video work.
Alas, network infrastructures have not kept pace with the computers which they connect. Though small data files can be transferred and shared quite effectively over conventional network interconnects, such as ethernet, these do not lend themselves to sharing and transferring large files. Thus, although users are accustomed to seemingly instantaneous file access over a network, it can take over an hour to transfer a 60 sec. video file that is 1.2 GBytes in length.
The prior art has developed interconnects that permit high-speed transfers to storage devices. The so-called fiber channel, for example, affords transfers at rates of up to 100 MBytes/sec--more than two orders of magnitude faster than conventional network interconnects. Although a single storage device may sport multiple fiber channel interfaces, no system has been developed to permit those workstations to share files on that storage device.
In view of the foregoing, an object of the invention is to provide improved digital data processing systems and, particularly, improved methods and apparatus of high-speed access to, and sharing of, disk drives and other storage devices on a networked computer system.
A related aspect of the invention is to provide such systems as can be implemented with minimum cost and maximum reliability.
Yet another object of the invention is to provide such systems as can be readily adapted to pre-existing data processing systems.
Yet still another object of the invention is to provide such systems as can be readily integrated with conventional operating system software and, particularly, conventional file systems and other input/output subsystems.